1. Field of the Invention
The invention relates to shellfish growth, and, in particular, to methods and apparatus for fostering shellfish growth. More particularly, the present invention relates to fostering the growth of oysters and the formation and creation of oyster reefs.
2. Description of the Related Art
Projections based on historic rates of erosion indicate that the Gulf of Mexico shore in some areas of coastal Louisiana will move inland as much as 25 to 30 miles within the next 50 years. These predictions are based upon measurements of rapid erosion of the barrier islands along the coast of Louisiana, erosion and deterioration of the coastal marshes, and subsidence. The erosion problem is exacerbated by the fact that the lowland soils and near-surface sediments inland of the existing barrier islands are composed largely of clays and organic peats and are almost devoid of sand-sized particles that might be reworked into new chains of barrier islands. Muddy shorelines are highly susceptible to erosion, while shorelines composed of sand, gravel, or shell can better absorb wave energies associated with open waters.
The ways in which sand, gravel, or shell can be introduced onto Louisiana's shores and beaches include deposition in the immediate vicinity of the active outlets of the Mississippi and Atchafalaya Rivers, dredging from buried sand or shell bodies, introduction from a distant source, and production of shell (calcium carbonate) by shell fish. While Eastern American oysters and clam shells have been dredged from Louisiana water bodies for many years, their use in shoreline management has been limited. The use of shoreline and bankline stabilization has application in many coastal and estuarine areas throughout the world.
Reef construction also can be expected to benefit fisheries production and diversity. Reefs are known to both aggregate existing populations of fish and provide secondary increases in production by providing additional forage in the form of attached and associated floral and faunal communities. Studies of artificial reefs have demonstrated that fish biomass may be from eight to thirty-five times greater than nearby control areas. In inshore waters of the Gulf of Mexico, man-made oyster reefs, planted by spreading cultch on the bottom, have been used to concentrate desirable fish species. Ecological studies have listed 170 species of plants and animals commonly associated with oyster reefs in the northern Gulf of Mexico region.
U.S. Pat. No. 4,788,937 discloses oyster bed fostering by distributing chunks of rubber or rubber chips on the bottom of a body of water. The chunks of rubber or rubber chips may be produced by chopping or shredding old rubber tires into pieces ranging in dimension from one to four inches.
U.S. Pat. No. 4,377,987 discloses a system for growing oysters including, in combination with a vertical row of trays suspended from carrying ropes and enveloped by a protection net where each tray has a rim and bottom net for holding oysters, a system for releasably fastening the trays to the carrying ropes; the fastening system includes converging notches of indentations in the rim of each tray and an enlarged detent on each carrying rope for releasably engaging the notches or indentations.
U.S. Pat. No. 4,186,687 discloses a method for growing oysters and other mollusks in which cultchless young oysters of a selected size taken from seed stock are placed in a first set of foraminous cribs and the first set of foraminous cribs are then placed on a shelf within an open top receptacle where the young oysters are protectively housed within the receptacle intermediate the top and bottom of the receptacle. Immature oysters of a larger size than the oysters placed in the first set of cribs are placed in a second set of foraminous cribs and the second set of foraminous cribs are placed across the open top of the receptacle above the first set of cribs. The second set of cribs are lashed to the top of the receptacle, whereupon the receptacle with its oyster containing cribs supported thereon are lowered to the bottom of a body of water where it is allowed to remain for a predetermined oyster growth period. The receptacle and trays may be raised periodically for inspection, and for culling from the second set of cribs the mature oysters, and for culling from the first set of cribs the immature oysters above a predetermined size which are then placed in the second set of cribs where they are allowed to reach maturity. The apparatus of this invention includes the receptacle described above in subcombination and in combination with the foraminous cribs.
U.S. Pat. No. 3,811,411 discloses a method of cultivating mollusks including enclosing discrete groups of seed mollusks lengthwise of the interior of the tube of netting material, lowering the resulting tube into an aqueous mollusk growth-inducing environment, and thereafter harvesting the grown mollusks.
U.S. Pat. No. 3,702,599 discloses a shellfish growout tray which is a device for sustaining the growth of shellfish, such as oysters and the like, including a one-piece, molded plastic tray including a bottom wall and four side walls providing an open top for the efficient loading of immature shellfish into the tray, the tray having stacking rails and tray supporting surfaces enabling the loaded tray to be guidingly moved into a stable operative stacked relation with a plurality of like loaded trays wherein adjacent trays define an operative growth space therebetween, the bottom wall being operative to support immature shellfish and provided with perforations permitting efficient unitary movement of the operatively stacked trays into and out of an operative position within the water environment of growth, the side walls being perforated so that when the tray is in such operative position sufficient water flow through the operative space is provided to nourish the growing shellfish while predatory water life is excluded therefrom, the height of the side walls being such that the operative space is sufficient to permit growth of the shellfish to maturity while insuring an efficient number of operative spaces within a given stack height.
U.S. Pat. No. 3,430,607 discloses a method of growing oysters by using a particulate gypsum oyster bed covering including distributing particulate gypsum on the bottom of a body of water adapted to the growth of oysters to form a bed, the gypsum being produced by acidulating phosphate rock with sulfuric acid in the manufacture of phosphate products.
U.S. Pat. No. 3,316,881 discloses an artificial oyster cultch including vertically spaced superimposed sheets, the sheets being suitable to set spat and having raised central portions and lower edge portions and alternately positioned crisscrossed members, and a connecting device for holding the sheets together in crisscrossed stacked relation.